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By using the built-in data-compression capability of the tape drive, greater data
rates than the native data transfer rate can be achieved. However, the actual
throughput is a function of many components, such as the host system processor,
disk data rate, block size, data compression ratio, SAS bus capabilities, and system
or application software.
Cartridge compatibility
The TS2240 uses the IBM TotalStorage
compatible with the cartridges of its predecessor, the IBM TS2340 Tape Drive. The
drive performs the following functions:
v Reads and writes Generation 4 cartridges to Generation 4 format
v Reads and writes Generation 3 cartridges to Generation 3 format
v Reads Generation 2 cartridges
v Does not write Generation 4 cartridge to Generation 3 format
v Does not write Generation 3 cartridges to Generation 2 format
v Does not write Generation 2 cartridges
v Does not read or write Generation 1 cartridges
The drive reads tapes that have been written by other licensed Ultrium 4 drives. It
also writes to tapes that can be read by other licensed Ultrium 4 drives.
In addition to using the IBM TotalStorage LTO Ultrium Data Cartridge with up to 800
GB capacity, the drive also offers read/write capability for certified LTO Ultrium tape
cartridges.
Speed Matching
To improve system performance, the drive uses a technique called speed matching
to dynamically adjust its native (uncompressed) data rate to the slower data rate of
a server. With speed matching, the drive operates at different speeds when reading
or writing the Ultrium 3 or Ultrium 4 cartridge format. Native data rates are as
follows:
v Ultrium 4 (Read/Write): 31, 40, 52, 67, 85, 105 and 120 MB/s
v Ultrium 3 (Read/Write): 30, 40, 50, 60, 70, or 80 MB/s
v Ultrium 2 (Read only): 15, 19, 22, 26, or 30 MB/s
If the server's net (compressed) data rate is between two of the preceding native
data rates, the drive calculates the appropriate data rate at which to operate. Speed
matching dramatically reduces backhitch, the condition that occurs when a tape
stops, reverses, and restarts motion. A backhitch is usually the result of a mismatch
between the data rates of the server and the drive.
Channel Calibration
System performance is further optimized by a feature called channel calibration, in
which the drive automatically customizes each read/write data channel to
compensate for variations in such things as the recording channel's transfer
function, the media, and characteristics of the drive head.
®
LTO Ultrium 800 GB Data Cartridge and is
Chapter 1. Product description
1-3
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